The present invention relates to filters for removing solid particles from a fluid stream. The invention is particularly directed to, and is therefore described below with respect to, filters for use in water irrigation systems for filtering out dirt particles in the water supply line which may tend to clog drippers, sprinklers, or other water irrigating devices.
The water used in water irrigation systems is frequently so laden with dirt that the filters used in such systems must be cleaned at frequent intervals. This increases the maintenance cost and the down-time of the filters. A number of automatically self-cleaning filters have been designed, wherein the filter is automatically reverse-flushed when the filter body has become so clogged with dirt particles as to produce a predetermined pressure drop. However, such automatically self-cleaning filters are usually of complicated construction and therefore costly to produce.
An object of the present invention is to provide new filter constructions having a self-cleaning capability effective to reduce the maintenance cost and the down-time of the filter.
In addition, water irrigation systems commonly include fertilizer pumps for pumping fertilizer solution into the irrigation water, and filters downstream of the fertilizer pump for filtering out solid particles which may tend to clog irrigation drippers, sprinklers, or other water irrigation devices connected to the line. Various types of fertilizer pumps are in use wherein the driving force is taken from the pressurized water from the water supply line. In such cases, the water used for driving the pump is drained to the ground and is therefore not only wasted, but also produces muddy nuisances around the pump, unless a special recovery container is provided which must be periodically emptied. In addition, the fertilizer pumps commonly used are relatively bulky and complicated and therefore add substantially to the cost of the overall system.
Another object of the invention, therefore, is to provide a combined filter and pump device having advantages in the above respects.